The information technology (IT) development allows the digitalization of many daily and business practices. Much information, such as documents, images, video, music and animations, is stored in PC, digital media or mobile devices. Internet enables further sharing of the digital information across borders and time restrictions. As a large amount of digital contents are created and shared, more and more digital contents are stolen and the privacy is violated. The security problem poses a real threat to the wider application of IT. The concept of digital right management (DRM) is a result of the need to regulate the authorization and sharing of information in order to provide protection over the information and related privacy issues.
A DRM technology championed by Open Mobile Alliance (OMA), called OMA DRM, can provide the protection and delivery management of the wireless digital contents. OMA DRM regulation ensures the use of digital contents on mobile devices, such as cell phones, and follows the usage right of the object to protect the intellectual property (IP) right of high value digital contents. In other words, the use of OMA DRM allows the digital content providers to exercise the rights in accordance with the digital contents, for example, free examination of DRM content in advance, legitimate delivery of the DRM content according to the access rights, and new business model supporting DRM content.
In other words, OMA DRM allows the digital content providers to use with the access rights configuration to perform content storage, protection and management so that the DRM mechanism can be added to the hand-held mobile devices, such as in Java, MMS, browser, and Email software as to provide content protection capability.
Basically, it is important to allow both digital content providers and mobile device users to control the perspective responsibilities in terms of the use of the downloaded media objects. The object downloading is the important means for the media object delivery between mobile devices, and DRM is the important mechanism for controlling the use of media objects when downloading. DRM allows the digital content providers to define access rights of the use of the media objects, and establish the relation between an individual media object and different access rights. Furthermore, different pricing policies can be defined based on different access rights.
Therefore, the digital content providers can provide users with the rights to free preview of media objects, and charge for different use of the objects. As the object price is determined by the use instead of the object itself, DRM can sell the rights to use instead of the media object itself, which makes more practical sense for media use as well as effective management of DRM.
In the OMA DRM architecture, it relies on the DRM agent for controlling the right object (RO) rights. However, how the DRM agent controls the RO rights is not defined. Therefore, when a DRM agent checks the RO or executes the content object (CO), the conventional technique may face the following threats, for example, as disclosed in the following documents.
William et. al. disclosed a bootstrap architecture, as shown in FIG. 1. The bootstrap architecture uses an Aegis ROM 101 to download an operating system 105 from a trusted network recovery host 103. The bootstrap architecture is for secure OS, mainly to prevent the illegitimate users while neither addressing the issue of attack from the legitimate users nor the key usage mechanism. If the user removes the Aegis ROM and rewrites the hacking program, the system will be compromised. For example, an assembly language can be used to rewrite the program to skip the serial number checking or the access right checking block.
U.S. Pat. No. 6,850,252 disclosed an intelligent electronic appliance system and method. The method to achieve DRM is to allow the intelligent electronic appliance to check the hardware before downloading, and the music or video provided by a server is to be distorted for that hardware. Therefore, the music or the video can only be played on that hardware. However, if the user uses assembly language or similar method to rewrite the program, this DRM can be bypassed.
U.S. Pat. No. 6,820,063 disclosed a method for controlling access to content based on certificates and access predicates, by using the association relation between the CPU of the computer system and the operation system to ensure that computerized method will not be replaced. This method checks the correctness of access predicate, OS certificates, and rights manager certificate to control the content access. This particular association is neither described nor regulated. How to upgrade or process when a bug exists in the OS is neither described nor regulated. The user may use the error in the OS to write a different program to access the CO of the executing DRM agent, or use the error in the OS to execute a memory dump to access the CO stored in the memory.
U.S. Pat. Nos. 6,330,670 and 6,327,652 disclosed a DRM OS and a load and identify DRM OS, respectively. Both documents presented the establishment of trusted identity, whose technique is to hash the OS and store the hashed OS in the CPU.
This type of trusted platform module (TPM) does not perform RSA encryption and identification; therefore, it cannot perform DRM rights protection stand-alone.
In addition to the above threats, the conventional techniques do not provide any solution when there is error in the DRM agent or in the OS.